Chain saws



C. J. TWEEDIE Dec. 18, 1955 CHAIN SAWS Filed March 23, 1956 INVENTOR J. TWEED/E ATTORNEY CHARLES United States Patent O 2,774,395 CHAIN SAWS Charles J. Tweedie, Fanny Bay, British Columbia, Canada Application March 23, 1956, Serial No. 573,482 1 4 Claims. Cl. 143-42 My invention relates to improvements in chain saws.

The objects of the invention are to provide means for mounting the saw chain within its supporting cutter bar whereby friction is reduced to a minimum, less wear occurs and higher operating speeds are possible; to provide within the cutter bar itself a reservoir for lubricating grease; to provide a chain saw wherein less likelihood exists of the chain breaking and endangering the operator; to provide means whereby a worn or damaged tooth may be removed from the chain and replaced by another with little loss of operating time, and to provide a chain saw permitting the use of a simplified form of saw chain tooth which is economical to manufacture and maintain in perfect cutting condition.

These and other objects will appear as the specification proceeds.

Referring to the accompanying drawings:

Figure 1 is an elevation of the invention on a reduced scale.

Figure 2 is a sectional view taken on the line 2-2 of Figure 1.

Figure 3 is a sectional View, partly in elevation, taken on the line 33 of Figure 2.

Figure 4 is a sectional plan view taken on the line 4-4 of Figure 1.

Figure 5 is a fragmentary perspective view showing the inner face of the cover plate for the tooth opening in the cutter bar.

In the drawings like characters of reference indicate corresponding parts in each figure.

The numeral 1 indicates generally a chain saw having a motor 2 provided with a housing 3 in which a drive shaft 4 is journalled as at 5. A cutter bar 7 is supported upon the housing 3 and is provided with the usual semicircular ends 8 and 9 and a peripheral edge 10. The cutter bar is made up of two side plates 14 and 15 which are held by spacer blocks 17 so as to define an interspace 19. The spacer blocks are applied to the inner face of the side plate 14 adjacent the peripheral edge of the cutter bar and said blocks are held in position and the side plates are secured together by means of grub screws 21 which extend through countersunk openings 22 in the side plate 15. The inner faces of the plates 14 and are provided with complementary grooves or ball races 25 which are disposed parallel to the peripheral edge 10 of the cutter bar and a pair of ovate complementary recesses 27 are provided upon said inner faces which recesses surround the drive shaft 4, see Figure 4, and the purpose of which will later appear.

The cutter bar 7 is secured to the housing by bolts 30 which extend through horizontal slots 31 formed in the wall of the housing adjacent the drive shaft and the cutter bar is provided with horizontal slots 32 through which the shaft 4, extends. The shaft 4 is non-rotatably fitted with a sprocket 33 which is housed in the ovate recesses 27 in the plates 14 and 15. An anti-friction bearing 35 is mounted upon the cutter bar and is secured thereto by any suitable means whereby said hearing may be adice justed lengthwise of the slots 32. Adjacent the bearing 35 a threadedlug 36 is mounted upon the plate 15 and is fitted with a horizontally disposed adjusting bolt 37 having a locknut 38.

The cutter bar is adapted to rotatably support an endless s aw chain generally indicated by the numeral 40 and made up of a plurality of connected links 41, see particularly Figure 3; Each chain link 41 is provided with a curved connecting hook 42 which enables it tobe hingedly connected to" complementary hooks on adja-' cent links byfsimply pressing the hook of one link transversely against another. Each link has a single cutting tooth 43intermediate itslength and a notch 44 on its under-edge which is adapted to be engaged by teeth of the chain sprocket 33. The teeth are apertured adjacent each end as at 45 to receive a pair of bearing balls 46 which are adapted to run between the races 25 of the cutter bar.

A gap 50 is formed in the lower edge of the side plate 14 which is rebated as at 53 along its marginal edges and is normally closed by a plate 54, as shown in Figure 5. The plate is obviously provided with a continuation of the race 25 so that when the plate is secured in position by screws 56 the chain teeth may travel completely around the cutter bar and the sprocket 33 riding entirely on the ball races. The plate 54 when removed provides easy access to the saw chain 40, either for its entire replacement or for the removal and replacement of a damaged tooth by a perfect one.

Adjacent the end 8 of the cutter bar the side plate 15 is fitted with a grease nipple 58 which communicates with the interspace 19 so that said interspace may be filled with a lubricating grease.

If it is found that the teeth of the sprocket 33 are not properly engaging the links 41 of the saw chain either at the time of assembly or due to wear after prolonged periods of use, adjustment may be made by slackening off the bolts 30 and the lock nut 38. The bolt 37 is then rotated to cause the cutter bar and the saw chain supported therein to move relative to the sprocket so that the links 41 engage said sprocket with appropriate pressure. When the bolts 30 are again tightened the chain saw is ready for operation.

During operation of the chain saw the bearing balls 46 being slightly smaller in diameter than the space between the races 25 and the apertures 45 are free to roll in a manner which is governed by the pressure exerted thereon by the saw chain. Normally the balls will have a rolling contact with the upper or lower arcuate surfaces of the races 25 and a slidingcontact with an adja cent portion of the peripheries of the apertures 45 or vice versa but in any case the chain will be journalled to the extent that wear will be considerably less than the conventional chain saw where the chain has sliding contact only with the cutter bar. It will be realized that as a tooth is cutting in the kerf of the wood the leading ball 46 will tend to ride on the outer edge of the ball race 25 and the trailing ball will ride on the inner edge of said race, so that the balls will roll freely and in any direction according to the position of the ball when in the race when work is being done.

What I claim as my invention is:

1. In a chain saw having a cutter bar and a saw chain adapted to encircle the cutter bar, said cutter bar having side plates defining a peripheral channel, each of said sideplates having a groove spaced from the edge of the cutter bar to form a pair of ball races, said chain being formed with links connected together in a single plane, each of said links having a pair of apertures, a bearing ball loosely retained in each of the apertures, said links being located in the channel and said balls being located in the races.

Q 2! I i 'h aw sl d s aim. mha eintth i. balls are loosely retained in the ball races whereby they 7 may be free to rotate in any direction according to 'the 1 22; ai1; a l buatwara at fiei s sl d v 'rih u r Pa ee thw s zn a the m v n of' said side plate.- a

3. In af cl'iairrsa vv having a ciitte V n w -9t tqnair lebw fl r m pain of 'side' lates sec red win space Lsiflil p mireb gmea wim ab M n a said 1. 1 3

Alla/t she a ew as '9 r 1 side plates having a gap intersecting the ball race groove and a plate demountably fitted to cover the gap, said plate having a ball race groove on one side extending Q ed a: cla m asisi.

across the gap and connected with the ball race groove References Cited in 'th'e fiie of this patent;

UNITED STATESPATENIS July-15; 1947 FoREIGN PATENTS" 706,560 Ger many May 29, i941 Marshal 1 et' al. Ndv. 7, 1950 

